When I pull back on the slide and very slowly let it creep forward and when the slide initially contacts the brass it instantly cocks the nose of the bullet downwards. As the slide moves forward further, the round will either jam against the ramp in the slight nose downward position or slide up and into the chamber. Is it normal for the round to nose downwards before moving upwards?
Yes, downward movement of the cartridge as the slide contacts it is normal on the 1911. It's not uncommon however to hear of feeding problems related to this, or what is commonly referred to as the nosedive
. There are a few different reasons for these kinds of feeding problems, but more often than not it's an issue of the bullet contacting the feedramp too low so that it jams rather than sliding up the feedramp as it is intended.
Now the problem here can be a couple different issues. In some instances it's simply a feedramp that's not been milled deep enough, and the solution then is to send the gun in for repair/modification to correct the feedramp. You can check to see if your feedramp is deep enough by measuring it with a set of calipers, and I want to say off the top of my head that the mil-spec on the 1911 feedramp is supposed to be .360" deep assuming like a 31 or 32 degree angle. I'd imagine in your instance however the feedramp is not likely the culprit if previously you were having no feeding problems.
So a second thing to consider if the feedramp is correctly milled is that the magazines are simply not sitting up high enough in the magwell, so that the rounds in turn are contacting the feedramp too low. This can be caused by mags that are simply sitting too low, feedlips that get bent and hold the cartridges too low in the well, or even worn mag catches that aren't holding the magazines high enough. I'd think that a simple solution would be to try a new mag catch, or if you have access to another 1911 then you might even try swapping mag catches to see if that resolves the problem. I wouldn't be surprised to see that this is your problem here.
Then of course, the simple fix to the nosedive as others have pointed out is something like a Wilson Combat magazine or a Tripp Super 7 rebuild kit. This is the most common solution to feeding problems, and it does indeed work well because these solutions make the rounds sit higher in the magwell so that they contact the feed ramp higher. If you have access to a Wilson mag or something similar you might try it and see if that resolves the problem, in which case you'd know then that the rounds sitting too low on the feed ramp are indeed your problem.
Hope that helps, and hope you're able to get it resolved!